Power feed mechanism



Oct. 13, 1953 w. A. ESCHENBURG ET AL POWER FEED MECHANISM Filed March 7,1951 5 Sheets-Sheet l llllblllm y/ll/i DAV 0 D. PETHGREW CLARENCEJOHNSON AT ORNEYS Oct. 13, 1953 w. A. ESCHENBURG ET AL ,0

POWER FEED MECHANISM 5 Sheets-Sheet 2 Filed March 7, 1951 Oct. 13, 1953w. A. ESCHENBURG ETAL 2,655,058

POWER FEED MECHANISM Filed March '7, 1951 V 5 Shets-Sheet s ="IiIIl/l/[14 \NVENTORS WILLIAM A. EscHENauRe DAVID D. PETTIG'REW CLARENCE JOHNSONATTORN S Oct. 13, 1953 w. A. ESCHENBURG ET AL 2,655,058

POWER FEED MECHANISM Filed March '7, 1951 5 Sheets-Sheet 4 DAVlD D.PETHGREW CLARENCE JOHNSON ATTORNEYS 1 Oct. 13, 1953 w. A. ESCHENBURG ETAL 2,655,053

' POWER FEED MECHANISM Filed March '7, 1951 5 Sheets-Sheet 5 INVENTORSFiQ- WI LLIAI W A. ESCHENBURG DAVID D. PETnsREw fix V CLARENCE JOHNSON4/0 ATTORNEYS Patented Oct. 13, 1953 UNITED STATES PATENT OFFICEPettigrew, Johnson,

Milwaukee, Wis., South Euclid,

and Clarence Ohio, assignors to Rockwell Manufacturing Company,Pittsburgh, Pa., a corporation of Pennsylvania Application March 7,1951, Serial N 0. 214,284

23 Claims. 1

This invention relates to power feed mechanisms and more particularly toan improved construction adapted primarily for use as a drill feedmechanism.

The present invention is primarily concerned with improvements inhydro-pneumatic feed mechanisms of the type disclosed in application ofClarence Johnson Serial No. 133,922 filed December 19, 1949, forHydro-Pneumatic Power Mechanism for effecting rapid movement of a drillor other machine tool into and out of operative working engagement witha workpiece and .relatively slow feed movement during working engagementof the tool.

In apparatus of this kind, the positioning of the :machine tool withrespect to the workpiece is effected by a power piston and two or morecontrol pistons, the rate of movement of the power and control pistonsbeing determined by one or more .control valves suitably arranged in ahydro-pneumatic circuit.

It is an important object of the present invention to provide a novelconstruction of the elements and related circuits of such ahydropneumatic mechanism to materially decrease the size and weight ofthe apparatus while increasing its operating efficiency and itsadaptability for production by quantity production methods.

It is a further object to provide a novel control valve for such a feedmechanism.

It is another object to provide a novel quill and spindle constructionfor an hydro-pneumatic drill feed mechanism.

It is a further object to provide an improved feed rate adjusting meansfor a power feed mechanism.

It is another object to provide an improved power feed mechanism havinga minimum number of compactly arranged structurally rugged parts adaptedfor production under quantity production methods.

It is a further object to provide a novel construction for a power feedmechanism which facilitates manufacture, assembly and repair, therebydecreasing the costs of fabrication and maintenance of the mechanism.

It is a further object to provide a novel positioning and supportstructure for a power feed mechanism.

It is an additional object to provide a novel construction for ahydro-pneumatic power feed mechanism which facilitates bleeding and.filling the mechanism with operating fluids.

It is also an object to provide an improved drill feed mechanism whichincorporates a. novel 2 means for compensating for internal volumechanges occasioned by relative movements of the components of theapparatus.

Further objects will become apparent as the description proceeds inconnection with the accompanying drawings in which:

Figure l is a side elevation of one form of an improved power feedmechanism made in accordance with the present invention;

Figure 2 is an end elevation of the mechanism of Figure 1;

Figure 3 is an enlarged sectional View taken along line 3-3 of Figure 2illustrating the power section and a portion of the control section ofthe improved mechanism;

Figure 4 is an enlarged sectional view of the control section takenalong line 44 of Figure 2, line 4-5 being shown also in Figure 5 forclarity of illustration;

Figure 5 is an enlarged sectional view taken along line 55 of Figure 1,line 55 being shown also in Figure 3 for illustrative clarity;

Figure 6 is an elevation of the end cap for the control section of themechanism of Figure 1;

Figure 7 is an enlarged fragmentary sectional view taken along line 11of Figure 2;

Figure 8 is an enlarged fragmentary sectional view taken along line 88of Figure 2;

Figure 9 is a fragmentary sectional view taken along line 99 of Figure8;

Figure 10 is a sectional view of the control valve taken along line I0-4 0 of Figure 4;

Figure 11 is an enlarged fragmentary sectional view of a modifiedcontrol valve, adapted for use in place of the control valve of Figures4 and 10;

Figure 12 is a right end elevation of the valve body of Figure 11;

Figure 13 is an enlarged fragmentary plan view of one of the valveelements of Figures 3 and 11;

Figure 14 is a sectional view similar to Figur 3 of a modified form ofthe invention;

Figure 15 is a top plan view of the mechanism of Figure 14 partiallybroken away to illustrate internal constructional details.

Figure 16 is a vertical sectional view taken along line Iii-l6 of Figure15 of one of the control cylinders.

Figure 17 is a fragmentary sectional view of a locking mechanism for thestroke adjusting means in the mechanism of Figure 14; and

Figures 18 and 19 are sectional views of the control section of themechanism of Figure 14 taken along lines lB-IB and i9i9, respectively ofFigure 14.

Referring to Figures 1 and 2, [5 indicates the power section of theimproved feed mechanism to which a control section indicated generallyat I6 is rigidly attached as by bolts H. A stroke adjusting unitindicated generally at l8, through which one end of a combined powerpiston and drill quill-spindle unit [9 passes, is mounted on the frontend surface of power section [5, and a speed control unit, indicatedgenerally at 20, is mounted on the front end surface of control section[6, as more fully described hereafter. A pair of cover plates 2! areattached to the rear of the power section I 5 as by screws 22 to protectthe driving mechanism from dust, water, and other abrasive and corrosiveforeign matter.

Referring now to Figure 3, and particularly to power section 15, 23indicates a main body nous"- ing cast from relatively inexpensive metaland having mounting flanges 24 disposed at opposite ends along its lowersurfaces. As shown in Figures 1 and 2, smooth, flat, verticallyextending mounting pads 25 are formed on the opposite sides of housing23 to provide mounting surfaces by which the drill mechanism may bemounted in a variety of common machine tool supports. The pads 25 areaccurately machined so that the drill unit will be held in positivelongitudinal and lateral alignment with the support on which it ismounted.

The cast housing 23 is of hollow cylindrical construction provided atits opposite sides with inwardly directed annular flanges the innerannular Walls of which are accurately machined to provide alignedcircular bores 25 at it opposite ends. These bores are adapted toreceive carefully machined high grade steel sleeves or inserts 21 and28, preferably with a close machine fit. To assure proper alignment ofbores 23 and uniformity of size, these bores are preferably formed in asingle straight-through boring operation obviating the necessity of thetime consuming and expensive back boring operation and finishingmachining operations that would be necessary if the housing wereinitially a solid casting. O-ring seals 27a and 28a are provided onsleeves 27 and 23 respectively to maintain the respective inserts influid tight engagement with bore 26.

The outer surface of an annular peripheral flange portion 29 of sleeve28 is provided with an annular groove 30 which is in communication withthe inner surface of the sleeve through a plurality of circumferentiallyspaced ports 3|. A passage 34, having an enlarged portion in which asealing ring 35 is held, passes through the upper surface of housing 23in register with groove 30. Sleeves 2'! and 28 are maintained inabutting relation in bore 26 by shoulders 31 and 38 of annular housingextension members 39 and 40 respectively which are rigidly attached toopposite ends of housing 23 as by bolts (not shown) to form cylinderheads for the power cylinder which comprises sleeve or inserts 21 and28.

Housing extension 39, at the end containing shoulder 31, is providedwith an axially extending shoulder 4| of reduced diameter defining anannular space to closely receive the adjacent end of sleeves 21 and atits other end is provided with an annular motor mounting flange 42. Thebore of extension 39 at the shouldered end is slightly reduced indiameter and carefully internally machined for a purpose to be presentlypointed out.

Housing 23 and its extension members 39 and 40 are designed to receivethe main power piston of the power feed mechanism and the connectormembers adapting the power piston for connection to whatever device orelement it is to operate. In the preferred form of this invention,housing 23 and members 39 and receive the novel combined Ipower pistonand drill quillspindle unit l9 which is provided with an enlarged pistonportion 43, having suitable sealing rings 44, reciprocably receivedwithin sleeve 21, in fluid tight relation thereto. Reduced portions 45and 46 of quill l9 respectively reciprocably engage the reduced bore ofend member 39 and the inner sleeve 28. The bore of end member 39 andsleeve 28 are provided with suitable sealing means to define sealedchambers 47 and 48 on opposite sides of piston portion 43, the shoulder4| of extension member 39 also being provided with a sealing ring 43a tocomplete the seal for chamber 41.

Rotatably supported by mean of a preloaded bearing cartridge indicatedgenerally at 58, within a further reduced section 43 of quill I9, is adrill spindle 52 having a tool chuck 53 at one end and an elongatedsplined section 54 at its other end. The bearing cartridge 55 preferablypreloaded to prevent random axial movement of the spindle 52 withrespect to the quill l9 and is preferably of the general constructiondisclosed in United States Letters Patent No. 2,452,089. A suitablesealing structure indicated generally at 5| is provided at the forwardend of quill 19 to prevent the entrance of coolant, lubricant, and otherabrasive or corrosive foreign matter which may be present on the surfaceof chuck 53 into the interior of quill l9 and bearing cartridge 50.

A drive shaft 55 connected to any suitable power source, not shown, isprovided with a keyed adapter 56 carrying an elongated driving sleeve 51adapted to transmit power through adapter 56, to spindle 52. Whilesleeve El may be connected to adapter 53 and spindle 52 in any suitablemanner, the present invention contemplates the provision of fibreinserts press fitted in the ends of sleeve 51 and respectively providedwith internal splines 58 and a securing pin 59 at the end connected toadapter 58 and splines 60 alone at the end connected to spindle 52. Thisconstruction automatically compensates for any slight misalignmentbetween adapter 55 and spindle 52 yet assures a relative free sliding,non-binding driving connection between the axially reciprocable spindle52 and the relatively axially immovable sleeve 5?.

Referring now to the stroke limiting unit 23, an annular cap 63telescopes over the reduced annular portion 64 of housing extensionmember 40 and is held in place by a centrally apertured end plate 65,which is secured to extension portion 54 as by screws 66. Held betweenplate 55 and extension 64 is an annular outboard bearing 61 whichslidably supports quill portion .9 and is notched to receive a brassscraper ring 63 and a brass bushing 69. A grease fitting "i3 ispositioned in cap 63 through which grease is supplied to the annularspace between cap 53 and extension portion 54 and through registeringpassages 14 and 15 in extension portion 54 and bearing 51 respectivelyto an annular groove 76 in bearing 61. The length of extension portion64 and cap 63 are so proportioned that cap 63 will be held againstrelative axial movement with respect to housing extension 40, but willbe sufficiently free to permit relative rotative movement around housingextension 40.

The forward stroke of quill-spindle unit I9 is determined by theposition of an annular stop T! which threadedly engages the internalsurface of extension portion Gland is provided with an axially extendingslot I8. Received in slot I8 is a rod 59 which is rigidly attached as bya screw 3| to an annular collar 80 which is rotatably mounted within endmember 40. An idler gear 84 is mounted for rotation on a shaft 85, bothof which are received within slots in housing extension 40. Gear 84meshes with internal gear teeth in cap 93 and with external teetharranged around the periphery of the reduced end portion of collar 90.Rotation of cap 53 thus produces opposite rotation of collar 80, rod 19and stop 'I'I efiecting axial movement of stop 11 along portion 54 ofextension 40 to vary the ra'nge of movement of quill I9. As shown inFigure 1, a scale 52 is provided on cap 63 forcooperation with areference mark 83 on the stationary housing extension 40 to assure rapidand accurate selection of the desired drill stroke. A locking screw 35(Figure 1) extends through housing extension 40 into collar 30 to lockthe stroke adjusting unit it in its adjusted position.

The stroke adjusting unit [8 is here described only so far asisnecessary for a complete understanding of the present invention and ismore fully disclosed and 'claimedin copendin'g application Serial No.133,922 of Clare'nce Johnson filed December 19, 1949, forHydro-Pneumatic Power Mechanism and owned by the assignee of thisapplication.

Referring now to the control section I6 (Figures 3-7), 81 indicates acast housing of shell like form, the central portion of which is open atone end and along its lower surface. The housing 91 is secured to thepower section 23 by bolts I'I (Figures 1 and 2), with a carefullymachined lower surface of the closed end of housing Bl in fluid tightengagement with a similarly machined upper surface of housing 23 at apoint adjacent the passage 34 in the latter.

A machined surface of a cast cap 88 (Figure 6), having a pair of castfrusto-conical recesses 89 and 99 is secured to the machined open end ofhousing 8'! by means of bolts 9| (Figures 1 and 4). Machined cylindricalrecesses 92 and 93 terminating in machined shoulders 92a and 93arespectively are concentrically formed around the respective recesses 89and 90.

Threaded passages 89a and 90a extend through the cap 38 centrally of therecesses 89 and 90. The passages 89a and 90a are normally closed bythreaded plugs 89b and 90b, respectively. An upwardly and rearwardlyinclined passage 900 extends through cap 88 into the top of recess 90.Passage 900 is normally closed by a plug 90:1. The passages 89a, 90a and900 are provided to facilitate filling the mechanism with hydraulicfluid as more fully explained below.

A circular machined steel insert or valve body 95, having an enlargedflange portion 96 and an internal bore 9! is sealingly received within amachined bore 98 formed in the closed forward end of the housing 81. Thecenters of bore 98, valve body 95, and recesses 89 and 92 in cap 88 arelocated in axial alignment.

Valve body 95 is held in place by a nut 99 which threadedly engages areduced extension I00 of the valve body and draws flange 96 intoabutting engagement with a machined recess in the inner rings IOI aremaintained in fluid tight engagement between valve body 95 and bore 98the outer ring IOI being held in place by a washer I 92 clamped betweennut 99 and the outer surface of housing 01. A machined steel cylindricalinsert I03 is clamped between an annular recess 96a in flange 95 andshoulder 92a in the cap 88. Suitable sealing rings I04 maintain thecylinder I03 in sealing engagement at its opposite ends with recess 92and the annular outer surface of the recess 96a in the flange 90.

Sealingly received within a bore I05 on the forward end of housing 81,is a machined steel insert or cylinder head I96, generally similar tovalve body 95, having an internal bore I07 and an enlarged flangeportion I08. A key washer I09, positioned in an annular recess in valvebody I90 abuts a machined recess in a thickened portion I I0 of the endwall of housing 81 to prevent axial displacement of the valve body tothe right. A second machined steel cylindrical insert I I I, similar tocylinder I03, is sealingly clamped between shoulder 93a in recess 93 anda machined annular recess IiiSa in flange I08 of body I96 in the samemanner as cylinder I03. A pair of identical free pistons H3 and H4having centrally disposed plugs H3a and HM, respectively, arereciprocably received in cylinders III and I03, respectively. Each ofthe pistons has an O-ring seal I I5 in its head portion and a reducedportion H5 intermediate its ends to reduce the area of frictionalengagement between the pistons and the respective cylinder walls. Afluid passage I I! is provided in each piston to connect the inner andouter surfaces of the portion H6.

A movable abutment rod H2, extending through bore I01 into the interiorof cylinder I I I, is adjustably threaded into the outer reduced end ofbore IN and is held in adjusted position by a lock nut I I2a for apurpose to be explained. As clearly seen in Figure 4, abutment rod H2 isaligned with plug -I I3a of its associated piston H3.

A drilled pasage H8, in register with passages 34 and 35 extendsupwardly into housing 9'! and is the only fluid passage connecting thecontrol section I 5 with the power section I5. At its upper end, passageH8 is in communication with a drilled passage H9 (Figures 4 and 5)extending through the forward wall of housing 8?. Passage -I I9 isclosed at its outer end by a ball check filler valve I29 consisting of avalve body l2I threaded into the outer end of passage I !9, a springloaded ball I22 and a cap I23. Valve I29 provided a one way fillerpassage closed throughout normal operation of the drill mechanism, beingopened only for initially filling and refilling the system with asuitable hydraulic fluid.

Passage H9 is provided at its inner end with an enlarged, portion I24 inwhich one end of a machined tube I25 (Figure 4) is sealingly received.The opposite end of tube I25 is sealingly received within an enlargedportion I26a of a passage I29 extending through cap 88 drilled in axialalignment with passage H9. The passage I26 is normally closed by a plugI26?) threaded into cap 08. The length of tube I25 is 'prefer ablyselected so that it will be firmly clamped against the shoulders formedby the respective drilled portions I24 and I26a as cap 88 is drawn intoabutting engagement with housing 8'! by bolts 9|. Communication isestablished between recess 90 and passage 126 through a drilled passage121 in cap 88.

side of the'forward wall of housing 81. Sealing At a point intermediateits ends, passage I 18 is in communication with an annular groove I28 invalve body 95, as best shown in Figures 4 and 5. As shown in Figure 3,an internal annular groove I29, formed in bore 91 of valve body 95 isconnected to groove I28 through a plurality of circumferentially spacedradial ports I30. A valve core I35, having an internal bore I36, ispositioned within bore 91 of valve body 95 by means of external threadsI31 which engage internal threads I38 within extension I of valve body95. A keying pin I39 within extension I00 extends into an annular grooveI40 (Figures 3 and 11) in the valve core to limit axial movement of thevalve core. Communication between internal groove I29 and bore I36 isestablished through a plurality of angularly spaced arcuate grooves I43(Figures 3 and 10) in valve core I35. The inner end of core I35 liesadjacent a triangular metering orifice I44 (Figures 11 and 13) in thewall of a reduced portion I45 of valve body 95. A plug I46 is threadedinto the inner end of reduced portion I45. A ball check valve I41 isheld normally in resilient fluid tight engagement with a central boreI48 in cap I46 by a spring I49 positioned between ball I41 and one endof bore I36 in core I35.

Mounted on the outward end of valve core I35 is an adjusting knob I50.Relative movement between knob I50 and core I35 is prevented by a setscrew II extending through knob I50 onto core I35. Rotation of knob i50will, due to the threaded connection between core I35 and body 95, movecore I35 axially to control the effective size of the uncovered portionof metering orifice I44 for a purpose fully explained hereafter.

Due to the shape and arrangement of orifice I44 with respect to core I35and this threaded connection extremely fine adjustments of the meteringorifice can be effected.

A plurality of locking screws I52, extending through knob I50 ontoextension I00 of valve body 95, is provided to prevent relative movementbetween knot I50 and body 95 after a predetermined adjustment of theposition of core I35 has been made. The outer ends of screws I52 arepreferably disposed below the surface of knob I50 to accommodate adeposit of suitable sealing compound I53 to prevent tampering andunauthorized adjustment of the valve after it had been set up for aparticular job if this is desired.

A scale I54 is provided on the outer surface of the inner end of knobI50 for cooperation with a suitable reference mark I54 on housing 81 tofacilitate predetermined fine and accurate adjustment of the valveassembly.

Referring now particularly to Figures 4 and 5, a drilled passage I55extends vertically upward into housing 81 and is closed at its lower endby housing 23. At a point near its lower end, passage I55 is incommunication with a passage I56, similar to passage II9, drilledthrough the end wall of housing 81. Passage I56 is closed at its outerend by a threaded plug I51 (Figure 2,) and is provided at its inner endwith an enlarged portion similar to enlargement I24 of bore I I9 inwhich one end of a machined tube I59 is sealingly received. The oppositeend of tube I59 is sealingly received within an enlarged portion I60(Figure 6) of a passage I6I drilled into cap 88 in axial alignment withpassage I56. The length of the tube I59 is preferably selected so thatit will be clamped between cap 88 and the forward wall of housing 81upon application of cap 88. Fluid communication is established betweenpas- 8 sage I6I and recess 89 by means of a drilled passage I62 in cap88.

At a point adjacent its upper end, passage I55 opens into bore I05 at apoint in register with an annular groove I66 in cylinder head body I06Which is in communication with bore I01 through a series ofcircumferentially spaced ports I61. As shown in Figure 7, groove I66 isprovided at its lower surface with an inclined recess I68 which receivesa holding screw I69. As screw I69 is tightened, the valve body will bedisplaced to the right bringing washer I09 into firm engagement with arecess in the forward wall of housing 81 looking cylinder head body I06in position. A second annular groove I13, separated from groove I66 by aland I14, is in communication with bore I01 through a series of spacedports I15 (Figure 4) and through passage 176 in housing 81 with a pipeI11 which is threaded into passage I16 (Figure '7) and leads to a sourceof air under pressure.

Referring now to Figures 8 and 9, the space 41 to the left of powerpiston 43 is in communication with a conduit I18, which passes throughcover plate 2!, is threaded into member 39, and leads to a source of airunder pressure through drilled passages I19 and H91; in housingextension 39.

A guide rod I80, having opposed flat surfaces I8I, and opposed arcuatesurfaces I82 (Figure 9), which latter slidingly engage a bearing sleeveI83, pressed into an enlarged portion of bore I19, is pressed into arecess I84 in piston 43. It will be seen that while rod I preventsrotation of piston 43, it allows free longitudinal movement of thepiston and free communication between conduit I18 and space 41 at alltimes.

The operation of the mechanism thus far described is as follows:

Chamber 48, of power section I5, passages 34, H8, I26, I21, I28, I29,I30, bores 91 and I38, the space to the right of piston II4, tube I25and the space to the left of piston II3 are filled with a suitablehydraulic fluid or other liquid of low viscosity.

The filling operation is preferably performed with plug I26b and eitherplug 9022 or d removed so that air entrapped in the hydraulic circuitswill be bled from the highest point in the circuit. The power piston isheld in its fully forward position during filling. The piston H4 is heldin its corresponding fully forward position by a suitable push rodinserted through passage 89a after removal of plug 8%. The abutmentmember I I2 is screwed inwardly to hold the piston I I3 in its rearwardposition so as to be in proper operating position with respect to thepreselected position of pistons 46 and H4. Fluid may then be introducedthrough conduits 2I5 or plug I20 forcing air out of the hydrauliccircuit through passages I26, 90a and 900. As soon as a steady flow offluid through these passages is observed thepassages are closed. Asadditional oil is supplied, piston H4 is permitted to move to its fullleft position at which point the system is completely filled. As will beseen from Figure 3 there is a substantial volume of fluid in cylinderI03 to the right of piston II4 when the power piston is fully retracted.This space, which is completely filled by the above described methodconstitutes an oil reservoir to assure complete retraction of the powerpiston even after an appreciable amount of oil has been lost from thesystem. If necessary the piston may be moved through one or more fullstrokes to eliminate entrapped air. The plug 89b is then reinserted toready the mechanism for operation.

Conduits I11 and I18 are connected by suitable valves alternately to asource of air under pressure (not shown) or to exhaust (not shown) tothereby alternately connect chamber 41 of power section I and passageI13 or the space to the right of piston I I3, the space to the left ofpiston II4, passages I55, I56, I62, tube I59, and passages I66, I61,I13, I15 and I01 to air under pressure or exhaust.

Assuming conduit I18 is connected to a pressure source, conduit I11connected to exhaust,

and pistons 43, I I3 and H4 to be in the position shown, air underpressure will be supplied to chamber 41 at the rear of piston 43. Thisair acts to move the piston to the right, advancing chuck 53 whichcarries a suitable drilling implement (not shown) to the right toward aworkpiece. As piston 43 moves to the right fluid will be displaced fromchamber 48 through passages 34, H8, H9, tube I25, and passages I26 andI21 into the space to the left of piston Il3. Since the space to theright of piston H3 is vented to atmosphere through conduit I11, piston II3 will move rapidly to the right at a speed determined by the size offixed passage 34. Pistons 43 and H3 will continue to advance rapidly tothe right until piston II3 abuts rod H2. The position at which pistonII3 abuts rod H2 is, of course, determined by the adjusted position ofrod H2 and thus can be varied within wide limits.

When piston I I3 abuts rod II2, fluid can no longer leave the upper endof passage I I 8 through passage H9 and tube I25. However, as piston 43is still being urged to the right under the influence of the pressurizedair in space 41, the fluid to be displaced will now follow a secondarypath from passage I I3 through passages I28, I29, I30, I43, and bore I36of valve body 95 (ball I41 being held on its seat) and metering thenthrough orifice I44 into the space to the right of piston M4. Since thespace to the left of piston II 4 is vented to atmosphere through passageI62, tube I59, passages I55, I66, I61, I01, I13, and conduit I11, thepiston I I4 is free to move to the left under the influence of the fluidpassing through metering orifice I 44 at a rate determined by the sizeof orifice I44 which in turn depends upon the position of valve coreI35. It will be understood that by varying the shape of orifice I44 thecharacter of the flow adjustment effected per unit of linear movement ofcore I can be varied as desired. Since the extent of movement of pistonI I4 at this controlled rate depends upon the setting of rod H2 and theamount of liquid to be displaced, which is always maintained at asufiicient volume to permit the maximum permissible movement of piston43, piston 43 will continue to advance until the forward shoulder ofportion 49 abuts adjustable stop 11. It, therefore, will be seen thatthe advancement of piston 43 and chuck 53 through a preselected strokedetermined by stop 11 is effected at two controlled speeds, and that bysuitable adjustment of stop rod H2, the entire stroke as well as theportions of the stroke effected at each speed are subject to ready andprecise control. In practice, the drill head is adjusted so the drill iscarried to a point just short of the surface of the work at high speedand advances into the work at the controlled lower feed speed.

To return the drill to its initial position, conduit I11 is connected toa suitable source of air under pressure (not shown) and conduit I18 is,pressure is simultaneously supplied from conduit 111 through passagesI13, I15, I01, I61, and I66 ,of I06, passages I55, I56, tube I59 andpassages I60 and I62 to the left side of piston II4 urging it to theright. However, during the movement of piston I I3, the pressuredifferential across ball check I 41 is insufficient to unseat the checkvalve and there will be no fiow through passage I49 and due to thesubstantial equality of pressure on the opposite sides of passage I44,there will be no appreciable flow through passage I44 and consequently,piston II4 will be held stationary.

When piston I I3 abuts against cap 88, the pressure on the right side oforifice I44 and ball I41 will immediately be substantially decreased. A

pressure differential will then be established across ball I 41sufficient to overcome the force of spring I49. Ball I41 will then beunseated, and fluid will flow through passages I 48 and I 44, bores 91and I36, passages I43, I29, I30, I28, H8, and 34 into chamber 48 forcingpiston 43 to the left. This movement will continue until pistons H4 and43 are returned to their original positions, as shown in Figures 3 and4. It will be noted that, although pistons I I3 and H4 movesequentially, the entire withdrawal stroke of piston 43 is effected at arapid, substantially uniform, rate.

In certain machining operations, it is desirable Y that the entireadvancing and withdrawing stroke be effected at the relatively slow feedrate. To this end, the valve assembly 95 of Figures 3 and 4 may bemodified as shown in Figure 11, wherein the valve assembly there shownis identical to the valve assembly described above except for theconstruction of the valve core and the components assembled therein. Inits external construction, valve core I35a (Figure 11) is identical tovalve core I35 (Figures 3 and 4) except that transverse slots I and I9Iof differing depth are provided across its outer end. An extension I92of a control knob I93 is shaped so that it may be received in either ofthe slots I90 and I9I. Threaded into a central aperture in knob I93 is avalve actuator stem I94 reciprocably received within an internal boreI95 provided in core 13511. An enlarged portion I96 of stem I94 isreciprocably and sealingly received within an enlarged counter-bore I91of core I 35a. A spring I98, coiled about portion I96, is compressedbetween ball I41 and the end of a second enlarged bore I99 in valve coreI35a, spring I98 and bore I09 respectively corresponding to spring I49and bore I 39 of Figures 3 and 4. A second spring 200, coiled aroundstem I94, is compressed between the end of bore I91 and the shoulderformed by the enlarged portion I96 of the stem.

When knob I93 is withdrawn and extension I92 is placed in slot I9I, asshown in the dotted line position of Figure 11, valve stem I94 andenlargement I96 thereof is moved to the right to the dotted lineposition. In this position, the valve assembly functions exactly as thevalve assembly described above in connection with Figures 3 and 4.However, if the knob I93 is allowed to seat in slot I90, the knob andstem occupy the full line position of Figure 11 and the enlarged end I96of stem I94 is seated on ball I41 under the influence of spring 200which is of sufficient strength to maintain ball I41 seated throughoutthe operating cycle of the drill head. Then, if abutment rod H2 is movedto the left so that it holds piston H3 against the left end of cylinder93, it will be seen that the only path provided for oil leaving andentering the chamber 48 will be through metering orifice I46. Thus, allmovement of piston I43 on both the advance and return strokes will beeffected at the feed rate determined by effective size of orifice I44.If desired, the abutment rod II2 may be moved to the right to allow anydesired movement of piston I I3. If the knob I93 is then placed in itsfull line position (Figure 11), the initial portions of both theadvancing stroke and the withdrawal stroke will be effected at highspeed, and the final portion will be at feed speed. The relative lengthof the high and low speed portions of the stroke will be determined bythe amount of travel of piston I I3 and can be varied at will bysuitable adjustment of rod I I2.

As the piston 53 reciprocates, it will be apparent that the volume ofthe space 20I between the forward shoulder of portion 46 of the pistonand the stop El will vary and that this variation will be accompanied byundesirable pressure resistance in this space. Particularly, as thepiston is rapidly withdrawn, a vacuum will be produced in space 2M whichmay draw coolant and lubricant and in some cases, small metal chipswhich may be on the surface of quill l9, into the space with consequentdamage to the accurately machined components of the drill head. Tostabilize the pressure in the space 20 I, a vent comprising registeringdrilled passages 204 and 205 in head 40 and the base of housing 23,respectively, is provided. A fine screen filter 296 is connected to theouter end of the vent passage to maintain the chamber free from grit anddust, which may be present in the surrounding atmosphere.

The mechanism as a whole readily lends itself to semi-automatic or fullyautomatic control. By the proper employment of suitable switches andrelays effective to control solenoid actuated valves in conduits I11 andI18, the mechanism can be automatically operated in response to a numberof control factors. For example, a conventional pressure switch may beconnected to the forward end of chamber 48 or to the liquid passage ofcontrol section I6 to signal a withdrawal of the drill when thehydraulic pressure at the forward side of piston 93 or in any part ofthe control section falls below a predetermined minimum due to theabutment of the quill against stop 11 or the build-up of excessivepressure at the drill point. Means responsive to the drill torque or tothe motor current may alternately be provided to signal a withdrawal ofthe drill. In some cases, it will be desirable to combine pressure andtorque responsive control means. Where drill pressures and torques maybe too small to provide reliable control, an independent timer may beused to control the system. It may also be desirable to supplement thetimer with a pressure switch, the latter operating only on completion ofthe drilling operation or under condition of severe overload.

Advance of the drill may be initiated by a switch which is actuated bythe quill in its withdrawn position.

A typical automatic switch system is illustrated briefly in Figure 3,wherein numeral 2I0 indicates a housing, supported by any suitable means(not shown) accommodating a two-position switch, set to one position bymechanical action and to the other position by a fluid pressureresponsive element. The switch, for example, may be mechanicallyactivated by depression of a pin 2 I I, extending through housingextension 39 at a point opposite the end of end portion 45 of quill I9in its fully withdrawn position. When the switch is so activated, leads2I2 and 2I3 are energized to activate suitable solenoid-operated valves(not shown) to connect conduits I18 and Ill to pressure and exhaust,respectively, initiating an advance stroke of quill unit I9. Whenforward movement of the quill is arrested by stop TI or by excessivepressure at the drill point, the pressure in space 48 will rapidlydecrease. This pressure decrease is transmitted through passage 3| insleeve 23, a drilled passage 2M in housing 23, and a fluid conduit 2 I5,to the pressure responsive switch element in housing 2 I 0. Leads 2I5and 2H are then energized, reversing the position of the valve inconduits I11 and I18, effecting a withdrawal of the quill unit. Thecycle may be repeated indefinitely or may be interrupted at any point byoperating suitable manual switches (not shown) which break the circuitin either leads 2I2, M3 or 2I6, 2|! preventing energization of the saidsolenoid operating valves.

Other suitable automatic control systems are developed in the copendingapplication of Clarence Johnson, Serial No. 133,922, referred to above,and application Serial No. 137,605, of Clarence Johnson for SwitchMechanism and Control Circuit for Hydro-Pneumatic Power Mechanism, filedJanuary 9, 1950, both owned by the assignee of the present application.

The modified mechanism illustrated in Figures 14 to 19 is, in its majoraspects and in function, substantially the same as that above describedin connection with Figures 1 to 13, and accordingly, insofar as possiblethe same reference numerals are used to indicate similar parts in thismodification.

A number of detailed refinements have been incorporated in the modifiedmechanism to further reduce manufacturing and assembling costs, toassure the elimination of air pockets in the hydraulic circuit, and tofacilitate bleeding and filling these circuits. Because of the closesimilarity between the two forms of the invention, the mechanismillustrated in Figures 14 to 19 will be described only insofar as isnecessary to explain the points of distinction between the twomodifications.

Referring now to Figure 14, 250 indicates generally the power section ofthe modified feed mechanism to which a control section indicatedgenerally at 252 is rigidly attached as by studs 253 and nuts 255(Figure 18). A stroke adjusting unit indicated generally at 254 throughwhich one end of the combined power piston and drill quill spindle unit256 passes is mounted on the front end of the power section 250.Suitable cover plates for the mechanism, not shown, may be provided asrequired to protect the mechanism from objectionable foreign matter.

The power section 250 includes a main body housing 258 of hollowshell-like cylindrical construction provided with suitable externalmounting and aligning pads previously described. Cylindrical inserts orsleeves 260 and 26I are received within the body section 258, the formerbeing provided with a sealing ring 262 at one end. Sleeve 26I is adaptedto receive an outer sealing ring 263 and an inner sealing ring 265.

13 A washer 26511 is desirably formed of soft metal such as Babbittmetal, so any particles entering through sleeve 26I will be ground intothe washer to prevent scoring the quill, washer 265a retains the ring265 in proper position in sleeve 26L The outer surface of sleeve 26] isprovided with an annular groove 266 into which a plurality of angularlyspaced drilled passages 26'! extend to establish fluid communicationbetween the interior of sleeve 260 and. the outer periphery of thesleeve 26L To facilitate installation of the sleeve 26] without damageto the machine inner surface of the body section 258, a slight clearance is provided at the peripheral flange portion of sleeve 26lextending inwardly of the roove 266. It will be noted that sleeve 26I isof substantial length to provide an adequate bearing support for thepower piston 268.

Housing extensions or cylinder heads 2'!!! and 2', respectively, closethe rear and front ends of the body section 258 to which they arerigidly secured as by bolts not shown in a manner previously described.The power piston 268 is of generally the same construction as the piston45 previously described except that a. machined sleeve 269 is pressfitted onto the reduced forward portion of piston 268 and reciprocateswith close fit within sleeve 261. Also a plurality of circumferentiallyspaced passages 212 are provided to establish communication between theinterior of the piston and the enclosed chamber 214 within the strokeadjusting unit 254.

The interior of the piston 268 is also connected to the expansiblechamber within the axially fixed drive sleeve 216 through spacedpassages Zll. Thus the spaces 214 and 215, the volumes of which varyinversely in substantially equal amounts during movement of the powerpiston, are vented to each other and changes in the internal volume ofthe power section are thus internally compensated for.

A vent port 218, into which a dust filter 219 is threaded, is providedto vent the power section to accommodate any slight inequalities whichmay exist in the variations in volume of the spaces 214 and 215.

A spindle 26! is rotatably supported within the piston 268 by means of asealed pre-loaded hearing cartridge indicated generally at 282. Anannular outer pre-loading member 233 is threaded into the forward end ofthe piston 268, the inner pro-loading member 284 being threaded onto theforward end of the spindle. The forward end of the spindle is enclosedby a dust cap 285 also threaded onto the end of the spindle, the cap 235providing a labyrinth seal at the forward end of the bearing.

ihe simplified stroke adjusting mechanism 254 includes a cap 285 whichtelescopes over the reduced forward section of the closure member 2' andis fixed against axial movement by a plurality of cap screws 288threaded into cap 286, and having sharp extensions which extend inwardlyof cap 286 into a peripheral annular groove in the member 21!. Anannular cover plate and sealing ring structure 230 is secured in anannular recess formed in the forward end of the cap 286 as by screws29!. Press fitted into a drilled bore in the cap 286 is rod 294 whichextends axially through a notch in an annular stop nut 296 threaded intothe bore of closure member 22!. It will be seen that when cap 286 isrotated, nut 296 will be threaded axially into or out of space 214 andwill thus provide an adjustable stroke limiting abutment for the forwardshoulder 29'! of the power piston. In this connection, it will beunderstood that rod 294 is disposed radially outward a distancesufficient to clear sleeve 269 of piston 268.

A means for locking the cap 286 in its adjusted position is illustratedin Figure 17 which is a sectional view in a plane approximately 30 fromthe vertical behind Figure 14. The upper surface of member 21! which isflat and appears nearly flush with the cap 286 in Figure 14, is off-setwith respect to the cap in the plane of Figure 17 so that a shoulder isformed therebetween. A locking stud 302 is threaded into the corner ofthis shoulder at an angle of approximately 45. A look washer 304 on stud302 is provided with a beveled surface which engages the cap 286 and thevertical shoulder of member 21 I, and thus locks the cap in adjustedposition. A conduit 298 threaded into a passage 289 which leads to theforward side of the piston 25% is provided to supply a Volume ofpressure fluid for the automatic actuation of a suitable control sectionwhich may take any of the forms pre viously described.

Except for the above noted features, the power section 250 issubstantially the same as the power section l5. The single passage 3H]leading to annular groove 266 also communicates with the novel controlsection 252 now to be described.

The shell-like control section 252 is comprised of three members, a mainbody section 320, a cap 322 and cover plate 324. The body section 322comprises a relatively thick forward wall 325 which joins at its loweredge an integral right angularly extending section 326. The member 320is machine finished along a portion of the outer surface of section 326so as to tightly engage the upper machined surface of the power sectionhousing 258 to which it is secured by the studs 253 and nuts 255.

The forward wall 325 is provided with parallel spaced bores 328 and 329and intercommunicating vertical bores (not shown) substantially asdescribed in connection with the housing member 81.

An annular machine steel insert or valve body 339, which, except forslight changes in proportioning, is identical to the valve body isreceived in the bore 328 and secured in place by a. nut 332 aspreviously described. A liner 353 is provided in the inner end of thecentral bore in the valve body 339 to guide the ball check valve is?into and out of seating engagement with plug I46. The adjustable valvecore 354 differs from the previously described core I35 only in that thespring receiving bore 335 is provided with an axial extension 33? whichis in fluid communication with the hydraulic circuit of the mechanismthrough a plurality of spaced passages 335.

A machine steel insert or cylinder head t lt Figure 16 is fitted intobore 329 with a machined shoulder 3&2 held in tight engagement with amachined recess 3:23 in the wall a nut 344 threaded on to the portion ofthe cylinder head extending externally of the wall 325. A washer 855 isclamped between the nut 3 M and the wall 325 to hold a sealin ring 385in place in bore 329. The interior bore of the cylinder headv 356communicates with the air circuit of the mechanism throughcircumferentialiy spaced passage 3453 and an annular groove in registerwith air circuit passages of the wall 325. A sealing ring 352 isprovided to prevent leakage toward the inner surface of the wall 325,The

I movable abutment member 354 is threaded int the head 345 andadjustably locked in place by a nut 355.

One end of a machine steel cylinder 353 is telescoped over a reduced endportion of cylinder head 35% against an annular machined shoulder. Theopposite end of the cylinder 353 is received within a machined bore 359in the cap 322. The opposite ends of a similar cylinder 362 are likewiserespectively telescoped over an annular machined shoulder on the valvebody 338 and received within a machined bore 364 in cap 322. Springwashers 363 are positioned between the ends of the cylinders 356 and 362and the bottom of the respective recesses in the cap 322 in which theyare received. The washers are provided to positively position thecylinders despite small variations in distances between the seatingsurfaces on which the cylinders are supported.

The cap 322 is secured at spaced points along its lower surface to thehorizontal section of the body 323 by bolts 368 (shown in Figure 15),machined surfaces being provided along the mating lines of the cap 322and the body 323.

At a point slightly off-set from the mid-point of its upper surface, thecap is secured by a bolt Sit to a spacer rod 312 (Figure 15) theopposite end of which is threaded into the wall 325 of the body 328. Theeffective length of the rod 372 is fixed by a lock nut 37%. Therespective lengths of the rod 3l2 and the cylinders 356 and 362 areselected so that when the cap is properly installed a slight clearanceis preferably provided at the washers 366 whereby the cylinders areyieldingly urged toward their respective opposite end mounting surfaces.

Clamped in a similar manner between the cap 322 and the wall 325 aremachined steel tubes Sit and which communicate respectively with thehydraulic and air circuits of the mechanism in the same manner as tubesE and IE9 described above.

The cover plate 324 extends over the top and sides of the controlsection between the cap 322 and the wall 325 and is secured at itsbottom edge to the body section 323 by plurality of screws 3H5. Theopposite ends of the cover 324 are received in peripheral recesses incap 322 and wall so as to be flush therewith.

Reciprocably received within the cylinder 356 is a solid free piston 382which is provided with a sealing O-ring 334. A plug 335 is pressed intothe center of the forward face of the piston 382 in alignment with theabutment member 354. A free piston 33%, having sealing rings 38! isreciprocably received in cylinder 362 and is provided with a centralrecess 363 of slightly greater diameter than the rearward extension ofthe body 339. The depth of the recess 333 is such that in the fullforward position of the piston, (which is never reached in the normaloperation of the mechanism, the normal forward position of piston 386being illustrated in Figure 14) plug Hi6 abuts the bottom of the recessand the port 543 is left partially uncovered.

As best illustrated in Figures 16 and 19, the machined recesses 396 and3&4 in cap 322 which receive the ends of the cylinders 356 and 362 areprovided with reduced extensions 332 and 394, respectively, with eachhaving a rearwardly and inwardly sloping wall so that the region ofgreatest depth is disposed upwardly and inwardly of the axis of therespective cylinders. As shown in Figure 14, a bore 396 extends throughcap 322 into the recess 394 in alignment with the axis of cylinder 362.This bore, which is normally closed by a threaded plug 398, serves as apassage through which a push rod may be inserted to position the piston386 against plug I45 during the filling operation as is explained morefully below. The end of hydraulic tube are is in communication withrecess 392 through an inclined bore 484 which extends to the outersurface of cap 322 and is closed by a threaded plug 463. A similarinclined passage 4G8 connects the air tube 318 and recess 394 and isclosed by a threaded plug M9.

A rearwardly inclined passage 452 (Figure 16) connects the upper portionof the recess 392 with the exterior of the cap and is closed by athreaded plug M4. The function of the several passages in the cap 322will be readily understood from a description of the method of fillingthe mechanism with hydraulic fluid presently to be described.

It will be noted that the filler plug I28 has been omitted in themodified apparatus, the hydraulic fluid being supplied through passage293 in the power section housing. In filling the mechanism, two factorsare of particular importance. First, the control pistons and 386 mustoccupy their proper relative positions with respect to the power piston268. Second, since the precise operation and control which characterizesthe mechanism is dependent in large measure on the action of theincompressible hydraulic fluid particular care must be taken to preventthe entrapment of air in the hydraulic circuit. The modified mechanismof Figures 14 to 19 is constructed to enable the ordinary mechanic tocontrol both of these factors with ease.

To begin the filling operation, the power piston is moved to its fullyforward position and plugs 398, 406, and 4 are removed.

A push rod is then inserted through bore 396 to place the piston 386 inits fully forward position. Abutment rod 354 is screwed into cylinder356 to hold the piston 382 in its fully retracted position. Hydraulicfluid at moderate pressure is supplied through passage 299 to the spaceat the forward side of the power piston and flows upwardly throughgroove 266 and thence through passage 3H) into the control section whereit flows through passages previously described to the forward side ofpiston 386. Because of the small clearance provided at the forward sideof this piston a very small amount of air will be entrapped there. Theoil also flows along tube 316 and through the passage 404 into space392. Since the bore 404 is at the highest position in the system, allthe air is bled ahead of the inflowing hydraulic fluid except the smallamount entrapped at the forward side of piston 386. To remove this airthe power piston 268 and control piston 386 may be reeiprocated througha number of cycles manually. To provide the necessary fluid reservoir atthe forward side of piston 386 as illustrated in Figure 14, plugs 406and 4M are installed and additional oil is added while piston 386 ispermitted to move to its full left position. Then by installing the plug398 in cap 322 and disconnecting the fluid supply lines the apparatus isready for operation. It is at the highest position in the system whetherthe mechanism is to be noted that either the passage 496 or 4I2installed in a horizontal or a vertical position. Thus the method offiling described will be equally effective in either position.

The operation of the device of Figures 14 to 19 is identical with theexception of the back feed 17 to that previously described in connectionwith Figures 1 to 13. Consequently, only the back feed operation will bedescribed here.

It will be recalled that retraction of the power piston at the slow feedrate to provide back feed as desired was accomplished in the apparatusof Figures 1-13 by the selective positioning of rod 19 (Fig. 11)

The modified mechanism of Figures 14 to 19 may be adapted for backfeeding either by the incorporation of a similar mechanism or by thesubstitution of a solid plug (not shown) for the apertured plug [46 andthe removal of the associated ball check valve. During the feed portionof stroke in either direction the hydraulic fluid thus flows onlythrough the feed port Hi4.

It is to be understood that because of the basic similarity of the twoforms of the invention, any of the modifications described in connectionwith Figures 14 to 19 may be readily incorporated in the mechanism ofFigures 1 to 13.

It will be apparent from the foregoing that the compact drill mechanismis ideally suited for manufacture with low cost, high speed factory massproduction assembly techniques.

Both the hollow cast housings for the power section and the controlsection require a mini mum of machining to put them in finished form.Such machining as is required may be performed in simple operations. Forexample, machining of the interior of the hollow cast power sectionhousing merely requires a single straight through boring operation sinceall of the interior finished surfaces are of the same diameter andconsist merely of aligned annular seating surfaces. The passages andapertures in the forward wall of the control section are alsorespectively of uniform diameter and readily accessible for ordinarythrough boring operations to simplify the finishing operation. Themating surfaces on the two housings are of minimum area and are allreadily accessible external surfaces whereas the cylinder and tubeabutment surfaces of the control housing are accessible also by ordinarythrough or counterboring tools. None of these drilled passages, bores orthe like is of inordinate length requiring special attention orcomplicated chucking of the housing to perform the drilling operations.

Further economies are affected by providing separable working part-s ofhigh grade steel thereby minimizing costs while assuring long life. Easyremoval and replacement of these parts, such as the cylinders, pistons,and other parts subject to the most rapid wear is also obtained. Thecylinders and pistons of the apparatus of Figures 1-13 are of identicalconstruction so they may be made on one machine set up whichsubstantially reduces the cost of manufacture and obviates the necessityfor maintaining inventories of a number of dissimilar parts and thepossibility of mi-sassembly incident to use of dissimilar parts.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to beconsidered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. In a hydro-pneumatic mechanism having a power section containing apower piston anda control section containing a plurality of controlpistons: separate shell-like housings for each of said sections havingfluid passages at their opposite ends; an external machined mountingsurface on one of said housings; a mating external machined mountingsurface on the other of said housings; means for connecting saidhousings in assembled relation and maintaining the said surfaces inengagement with certain of said passages in register; open ended,cylindrical inserts for each of said housings adapted to respectivelyrecipi'ocably receive said pistons and each having one end in fluidcommunication with said registering fluid passages to form a closedfluid reservoir and having their opposite ends in communication, throughothers of said fluid passages with a source of pneumatic pressureadapted to be selectively applied to said power piston or said controlpistons to effect desired operation of said mechanism.

2. In a hydro-pneumatic mechanism: a power section, comprising a firstcast shell-like housing for said power section having a machinedcylindrical bore, a machined power cylinder mounted in said bore,machined cylinder heads positioned at opposite ends of said bore influid tight engagement with said power cylinder, and a power piston insaid cylinder; a control section for regulating the movement of saidpower piston, comprising a second cast shell-like housing for saidcontrol section having an open end and a wall at its other end, aplurality of machined control cylinders mounted in said second housing,respective control pistons in said respective control cylinders,respective machined inserts mounted in and eX- tending through said wallfor supporting one end of said respective control cylinders, a capclosing the said open end of said second housing, and a plurality ofmachined clamping surfaces in said cap for clamping said controlcylinders against said inserts; securing means comprising machinedmating surfaces on each of said housings for securing said housings inassembled relation; and fluid passages in each of said housingsinterconnecting said power piston and said control pistons for tandemmovement by said fluid in said fluid passages.

3. In a hydro-pneumatic mechanism having a power piston: a controlsection for regulating the movement of said power piston comprising, ashell-like housing having fluid passages at one end, one of saidpassages communicating with said power piston; a plurality of open endedcylinders positioned within said housing; a control piston reciprocablyreceived in each of said cylinders; inserts in said one end of saidhousing having machined surfaces for sealingly engaging and supportingone end of each of said respective cylinders; a cap for said housinghaving machined surfaces for sealingly engaging and supporting theopposite end of each of said respective cylinders; and fluid passages insaid cap and said inserts through which respective opposite ends of saidcylinders are placed in communication with said one fluid passage toform a closed fluid chamber and the respective other ends of saidcylinders are placed in communication with a Source of pneumaticpressure adapted to be selectively applied to said control pistons toeffect desired operation of said mechanism.

4. In a hydro-pneumatic mechanism having a is power piston: a; unitarycontrol section having a plurality of control pistons and a fluidcircuit connecting said control pistons to a source of pneumaticpressure or exhaust and to a source of liquid confined between saidpower piston and control pistons for securing tandem movement of saidpistons comprising, a cast shell-like housing open at one end and alongat least one side face and having a wall at its opposite end providedwith independent first fluid circuit passages having ends openinginwardly toward said open end of said housing, one of said passagesforming part of a chamber for said confined liquid and communicatingwith said power piston; machined inserts extending through said wall andhaving respective machined seating surfaces facing toward said open endof said housing and having respective passages therein connecting. saidrespective seating surfaces to one of said first passages; a pluralityof open ended machined cylindrical inserts positioned within saidhousing with their respective adjacent ends sealingly supported onrespective ones of" said seating surfaces and communicating with therespective passage therein; respective control pistons reciprocablydisposed in said cylindrical inserts; a cast metal end closure caprigidly attached to the open end of said housing and having respectivemachined seating surfaces for sealingly supporting the respectiveopposite ends of said cylindrical inserts and respective passagesopening toward said wall and respectively communicating with saidopposite ends of said cylindrical inserts; and machinedtubes extendingbetween said wall and said cap and respectively connecting one passagein said cap to said inwardly opening end of the other passage in saidwall and said one of said passages in said cap to the inwardly openingend of said other passage in said wall to interconnect respective sidesof said control pistons and complete said' fluid circuit.

5. The structure of' claim l together with a valve positioned in one ofsaid inserts for controlling the flow of fluid through said one passagein said wall.

6. The structure of claim. together with a movable abutment extendingthrough the other of said inserts. into its respective cylinder forlimiting the stroke of said control piston therein.

'7. In a power feed mechanism having a power piston movable through anadvance and return stroke at a speed determined by the rate of flowpower section containing a fluid controlled power piston: a unitarycontrol section in flui'd communication with said power section forregulating the movement of said power piston, comprising a castshell-like housing open at one end and having a wall at its oppositeend; a plurahty of open ended machined cylinders in said housing in sideby side relation; a free piston in each of said cylinders; respectiveinserts extending through said wall having machined surfaces forsealingly engaging and supporting one end of said cylinders; a capattached to said open endof saidhousing and having respectivemachinedsurfaces for sealingly' engaging and supporting" the oppositeends of said cylinders; a plurality of tubes clamped between said walland ca-p'in, parallel relation to said cylinders; and respective fluidpassages in said cap for connecting oneend' of each of said tubes to arespective cylinder; and respective fluid passagesinsaid wall forconnecting the other end of one of said tubesand one end ofthe otherrespectiveadjacent cylinderend to said power section and for connectingthe other end of the other of said tubes-and its re:- spective adjacent.cylinder end to a sourceof pneumatic pressure adapted tobe selectivelyapplied to said power piston or said control pistons to effect desiredoperation of saidmechanism.

9. In a hydrmpneumatic mechanism having a power section containing apower piston and a control section containing a plurality of controlpistons: separate cast shelllike housings for each of said sections; anexternal machined mounting surface ononeofsaid housings a-matingexternal machined mounting surface on the other of said housings; meansfor connectingsaid housings in. assembled relation; open ended machinedcylinders in each of said' housings; a. freely reciprocable piston ineach of said cylinders; respective members removablymounted at oppositeends of each of said. housings,- each of said members having a machinedsurface for sealingly engaging and supporting; the adjacent: end of.said respective. cylinders; and fluid passages in said housings and saidmembers adapted to connect one side. of each of: said: pistons-toaclosed fluid circuit. and. the opposite. side of each. ofsaid pistonsto a sourceof pneumatic pressure: adapted to be selectively applied to.said. power; piston or said: control pistons: to effect. desired:operation of said mechanism.

10. In a hydro-pneumatic mechanism: a power section for moving a machinetool relative.- to a work piece: comprising a; cast shellplilw housing;axially spaced machined surfaces ins ternally of said housing}. amachined cylinder: frictionall'y mounted on saidimachined surfaces;vcast members mounted atthe: opposite ends; ofi saidhousing havingmachined. surfaces in! abut-i ting relation with opposite ends ofsaidlcylinder. and: forming therewith a fluid.chamber;; apistonreciprocably. received within said chamber, said. piston being adaptedtoe. carry. a machine: took. and fluid passages in eachv of saidmembersthrough which. the opposite; sides of said: piston: are connected to apower fluidicircuit anda con trol' fluid circuit.

11. In a hydro-pneumatic: mechanism: a power section for moving: a.machine: tool relative.- to a work piece, comprising, an openended. castshell-like housing; spaced". inwardly extending; machined surfacesadjacent opposite endsoi said: housing; amachined cylinder having.spaced machined surfaces positioned on said machined surfaces in said.housing;- cast members. at, opposite ends-of saidhousing in.abutting.relation with. the opposite ends of said' cylinder. and having machinedsurfaces engaging said machined surfaces in said housing; a. powerpiston reciprocably received within said cylinder; means for rotatablymounting a tool carrying device within said piston; a' fluid passageirrone of said members for connecting one side ofsaid piston to a closed;fluid: control circuit; a fluid passage in theother of saidmembers forcon necting the other side of said piston to apower 21 fluid circuit;and means associated with said piston and said last mentioned member forpreventing rotation of said piston while permitting free reciprocationthereof.

12. A hydro-pneumatic mechanism according to claim 11 wherein said lastmentioned means comprises an elongated rod rigidly attached to saidpiston and reciprocably received within said fluid passage in said lastmentioned member.

13. A unitary fabricated control section for a hydro-pneumatic mechanismcomprising a recessed cast body having an end wall and open at the otherend and along one side, the peripheral marginal side and end edges ofsaid one side and said open end being machined for respective matingengagement with a mounting surface of a machine tool and an end closurecap and said closed end having a pair of axially extending, laterallyofiset mounting bores therethrough spot faced around their inner endsand fluid passages respectively connecting said bores to the interior ofsaid body and at least one of said bores to the marginal end edge formedby said wall and the other of said bores to the exterior of said body; amounting insert disposed in each of said bores and each having acentral, axially extending bore and passage structure for placing theinner ends of said inserts in communication with its respective mountingbore; an annular, axially extending machined support surface of enlargeddiameter formed at the inner end of each of said inserts andintersecting a radially directed abutment shoulder disposed in axiallyspaced relation from said inner end; a cast end closure cap mounted onthe open end of said body having cored recesses disposed in respectivecoaxial alignment with said mounting bores and each having acounterbored annular, machined mounting recess in coaxial relation tothe respective mounting surfaces of said inserts and fluid passagesrespectively connecting said recesses to the interior of said body ininverse coaxial alignment with said fluid passages in said wall;respective machine steel cylindrical inserts extending between saidmounting surfaces of said inserts and its opposed mounting recess andsealingly engaged therewith; a freely reciprocable piston mounted ineach of said cylindrical inserts; and machine steel tubes extendingbetween and sealingly communicating with said coaxially aligned passagesin said wall and said cap whereby the opposite ends of said cylindricalinserts are cross connected to assure connection of the opposite ends ofsaid cylindrical inserts to said one bore and to the exterior of saidbore.

14. The combination defined in claim 13 wherein the insert in said onebore contains an adjustable bleed passage continuously open to the endof the cylinder mounted thereon and said other insert carries anadjustably abutment element adapted to predetermine the length ofmovement of the piston in its associated cylinder.

15. The combination defined in claim 14, wherein the first mentionedinsert also contains a second passage containing a one way valve adaptedto permit fluid flow from said end of said cylinder to said one bore.

16. A quill and spindle assembly for a hydropneumatic drill feedmechanism comprising a combined power piston and quill composed of anintegral tubular body having an enlarged annular piston portion,oppositely extending reduced diameter tubular end portions and ananti-rotation rod; axially spaced, internal hearing seats formed in oneof said tubular end portions, the inner seat at its innermost endterminating in an inwardly directed abutment shoulder; inner and outerbearing elements respectively disposed on said seats and including innerand outer races; an outer sleeve extending between said outer races, aninner sleeve extending between said inner races; a spindle carried bysaid inner races and having a body portion within said sleeve; a toolchuck of greater diameter protruding axially from one end of said bodyportion and beyond said outer bearing element and forming an abutmentshoulder at its juncture with said spindle body portion and a splinedsection of reduced cross section protruding axially from the other endof said spindle body portion and beyond said inner bearing element andinto said tubular body; a bearing retainer nut threaded on said spindlebetween said splined section and said inner bearing element and adaptedwhen tightened to clamp said inner bearing races and said inner sleevebetween said nut and said abutment shoulder of said spindle; and aretainer nut threaded in the end of said one of said tubular endportions and adapted when tightened to clamp said outer bearing racesand said outer sleeve between said last mentioned retainer nut and saidinwardly directed abutment shoulder.

1'7. In a hydro-pneumatic mechanism having a power cylinder, at leastone control cylinder, and a fluid circuit connecting said cylinders: avalve for controlling the flow of fluid in said circuit comprising, abody having a longitudinally extending central bore and longitudinallyspaced ports extending through said body into said central bore; a corein said central bore having one end extending out of said bore and anopposite end normally adjacent one of said spaced parts, a centralrecess opening through said one end, and ports connecting the other ofsaid spaced ports in said body with said central recess; and means tomove said core longitudinally in said body whereby said one end of saidcore adjustably covers a portion of said one of said spaced ports tocontrol the flow of fluid therethrough.

18. The combination defined in claim 17 to gether with an end closureelement for said bore having a fluid passage; a ball valve adapted toseat on one end of said fluid passage; and resilient means positionedwithin said recess in said core and engaging said ball to urge said ballagainst said one end of said fluid passage to normally close said fluidpassage.

19. The combination defined in claim 18 together with a longitudinalbore in said core, an axially movable rod extending through said bore insaid core, resilient means in said bore for urging said rod against saidball to maintain said ball in its seated position, and separate meansfor selectively rendering said resilient means ineffective to therebymaintain said rod out of seating contact with said ball.

20. The combination defined in claim 17 wherein said valve body includesa flange intermediate said spaced ports and an annular shoulder on saidflange for sealingly engaging and supporting one end of said controlcylinder between said spaced ports.

21. In a hydro-pneumatic mechanism having a power cylinder, at least onecontrol cylinder, a power piston and a control piston mounted in therespective cylinders and arranged to move in tandem; means forcontrolling the stroke of 23 said control piston :comprisingla {cylinder:head for :said control cylinder; .:a :shouldered flange on :said head;ior :sealingly supporting one end nf said xoontrol :cyl'mder; :a:reduced [section in :said headextending away dirom said oylinderandhaving a recess "opening :into said cylinder, isaid sextension alsohavingiatileast one fluid :passage for connecting said recessrselectiuely %to a source of pressure or exhaust; :and an abutment rodadiustably extending through said :recess into said cylinder forlimiting the LSUYOKB of said :control piston.

22. In a hydro-pneumatic mechanism :hauing an open ended control sectioncontaining :a pinrality of (open-ended tubular members; aplosure cap:comprisinrs ;a body having a machinedmarginal surface for engaging.:said -:control section at the open end thereof and {laterally :spaced:r eccsses ;for sealingly supporting :certain -;of said members;recessed :maehined euriaces for sealinglyrsupporting others of saidmembers, said :recessed machine surfaces being .formed around the=endsof passages in said cap leading :to said spaced recesses.

23. A quill and spindle assembly for :a hydropneumatic drill feedmechanism comprising :a combined power pistonand quill composed of anintegral tubular body having'an enlarged annula-r piston portion,oppositely extending reduced diameter tubular end portions and ananti-rotation mod; axially spaceddntemal bearing seats formed in zone,of said tubular and portions, :the inner :seat at its innermost endterminating an inwardly directed abutment shoulder; inner and outerbearing elements respectively disposed on :said seats :and includinginner and outer races; an outer sleeve extending between :said outer:races; an inner sleeve extending between said .inner races; aspindlecarried by said inner races and having means providing an abutment, andretaining means :on said -.one of :said tubular end portions and said:spindle adapted, respectivel-y. when tightened to clamp said outer andinner bearing races and sleeves :against the respeotive abutments onsaid one of said tubular end portions and said spindle.

WILLIAM ALBERT ESCHENBU-RG.

DAVID DAWSQN IPE'ITIGREW.

CLARENCE JOHNSON.

References Cited in the .file of this patent UNITED STATES PATENTSNumber Name 'Date 706,688 Reynders et a1 Aug. 12, 1902 1,069,995Anderson "Aug. 13, 1913 1,434,564 Ruetschi Nov. 7, .1922 1,948,115Johnson Feb. '20, .1934 2,114,389 'Kingsbury Apr. .19, 1938

